Third London attacker said to have been flagged to UK police

The fallout from the attack has eclipsed other issues in the political campaign ahead of Thursday's parliamentary election, with both the ruling Conservatives and opposition Labour Party battling to defend their records on security.

In particular, the revelation that at least one of the attackers, Khuram Butt, was well known to security services has raised concerns that they lack the resources to prevent attacks.

British police said the third assailant was Youssef Zaghba, 22, and that he had not been a subject of interest for them or the MI5 domestic intelligence agency.

But Italy's Corriere della Sera reported that Zaghba had been stopped at Bologna airport in 2016 when trying to fly to Syria via Turkey, and that Italian authorities had identified him as a potential "foreign fighter" and tipped off Britain about his movements.

Butt, a 27-year-old British national born in Pakistan, had appeared in a British TV documentary called "The Jihadis Next Door".

As details about the jihadists have emerged, Prime Minister Theresa May has faced questions about her record overseeing cuts to police numbers when she was interior minister.

The latest opinion poll on voting intentions, by Survation for ITV, had the Conservatives' lead over Labour narrowing to just one point from six points in the same poll a week earlier.

The consensus among pollsters remains that May's party, who have been in government since 2010, will win a majority. But a campaign email signed by May told Conservative supporters: "With the polls tightening and with just two days to go until polling day, we need to go all out with one final push."

Saturday night's rampage, in which Butt, Zaghba and Rachid Redouane drove into pedestrians on London Bridge before slitting throats and stabbing people in the bustling Borough Market area, was Britain's third Islamist attack in as many months.

Less than two weeks earlier, a suicide bomber had killed 22 adults and children at a pop concert in Manchester and, in March, five people died after a car was driven into pedestrians on London's Westminster Bridge.

Police had already named Butt and Redouane, a 30-year-old who claimed to be Moroccan and Libyan. An Italian investigative source said Zaghba was a Moroccan-Italian whose mother lived in the northern Italian city of Bologna.

All three men were shot dead at the scene of the attack by officers within eight minutes of police receiving the first emergency call.

The first of the dead to be named were Canadian Christine Archibald and Britons James McMullan and Kirsty Boden. The 48 injured included people from Britain, France, Spain, Australia and New Zealand.

Boden's family issued a statement on Tuesday, saying she had been a nurse and had tried to help the injured:

"As she ran towards danger, in an effort to help people on the bridge, Kirsty sadly lost her life."

A nationwide minute of silence was held at 11 a.m. to honour all the victims.

Before the recent attacks, Brexit and domestic issues such as the state of the health service and the cost of care for the elderly had dominated the election campaign.

When May called the election in April, her Conservatives led in opinion polls by 20 points or more.

But an announcement - made before the Manchester and London Bridge attacks - that they planned to make some of the elderly pay more for their care saw that lead start to shrink, and the trend has continued. Surveys now put the Conservatives ahead by between one and 12 points.

Security has become the number one issue and both main parties issued statements on Tuesday portraying their own positions on policing and intelligence as the most robust.

As interior minister from 2010 to 2016, May oversaw a drop of 20,000 in the number of police officers in England and Wales, which Labour leader Jeremy Corbyn has said should never have happened and warranted her resignation.

But the MI5 domestic intelligence service has seen its budget increase and has plans to expand to 5,000 officers from 4,000 over the next five years, MI5 chief Andrew Parker said last year.

Corbyn himself has faced repeated questioning over his own past views and actions on security matters.

He has been criticised for voting against counter-terrorism legislation and expressing reservations about police responding to attacks with "shoot-to-kill" tactics. Since the attack, he has said he fully supported the actions of the police.

Corbyn has also faced fierce criticism for past sympathies with the Palestinian group Hamas, Lebanon's Hezbollah, and Sinn Fein, the political arm of the Irish Republican Army, a guerrilla group that waged a violent struggle to take Northern Ireland out of the UK.

While the political debate raged, the investigation into Saturday's attack continued, with police searching an address in Ilford, east London, in the early hours of Tuesday.

Police had arrested 12 people on Sunday in Barking, also in the east of the city, where both Butt and Redouane lived, but released all of them without charge.

One of Butt's neighbours, Ikenna Chigbo, told Reuters he had chatted with Butt - known locally as "Abz" - just hours before the attack on Saturday and said he appeared "almost euphoric".

"He was very sociable, seemed like an ordinary family man. He would always bring his kid out into the lobby," said Chigbo.